A tape printing device prints labels that can be used to identify items like files, videotapes and audio cassettes and to facilitate their organization. Some tape printing devices also allow the operator to format the label in accordance with the operator's preferences.
Tape printing devices typically consist of a keyboard with character keys and formatting keys, a controller to create the label with the desired format, spools for holding an image receiving tape, a display for viewing the label prior to printing, a print head to print the label on the tape, a print head driving circuit to control the operation of the print head, a motor to control the movement of tape within the device and a cutting device to cut the label.
Some tape printing devices contain thermal print heads which have a matrix of heating elements. The print head driving circuit selectively activates the heating elements in accordance with the character or symbol to be printed. For example, to print the letter "A" on an image receiving tape, the driving circuit will activate only the heating elements of the matrix on the print head which are located at positions on the matrix corresponding to the letter "A".
An operator of a typical tape printing device types the text with the character keys, selects a format from selections shown on the display, views the label on the display prior to printing and selects a print key on the keyboard to print the label.
Tape printing devices in the prior art provide different formatting features to meet the labelling requirements of the operator. For example, the tape printing device described in EP-A-0 567 233 automatically scales the width of frames and the thickness of underlines according to a detected tape width. The tape printing device described in U.S. Pat. No. 5,562,353 also allows the operator to select the desired width of the frame and thickness of the underlines. Both tape printing devices have a limited formatting ability because they do not offer the ability to print frames with complicated shapes.
Tape printing devices in the prior art also provide more elaborate formatting features. For example, the tape printer described in U.S. Pat. No. 5,579,041 has the ability to print a frame with a complicated shape around text specified by the operator. The device displays a fixed number of frame portions which the operator selects and combines to produce the desired label. The device represents the frame portions as dot patterns which are stored in memory.
The tape printer has two disadvantages. First, the device requires a large amount of memory to represent each frame portion because the frame portions are represented as dot patterns. Second, the device can only offer the operator a limited number of frame portions to select because of the large amount of memory required to represent the frame portions.